In recent years, fiber-reinforced resin composite materials (hereinafter suitably referred to as “composite materials”) have been widely used in fields in which metal materials have been used so far. Among the composite materials, carbon-fiber-reinforced composite materials which are formed such that carbon fibers used as reinforced fibers, are impregnated with matrix resin such as epoxy resin, have a smaller weight and a higher strength than metal materials. Because of this, the carbon-fiber-reinforced composite materials are widely used in fields of sport activity articles, industrial machines, and aerospace.
Among these fields, in the field of aerospace, for example, in structures such as wings or a fuselage of an aircraft, a stiffened panel in which a skin comprising a composite material is integrated with a stiffener which is a lightweight metal frame member, has been used. As a typical stiffener, there is a stringer. Stringers are combined to conform in shape to the structure and supported by jigs. Plural sheets of prepreg are laminated (stacked) together with the stringers, and the resulting laminate is pressurized and heated in an autoclave. As a result, the prepreg is cured into the skin, and the stiffeners are adhesively attached to and integrated with the skin, thereby forming a stiffened panel.
As an exemplary structure comprising the stiffened panel, as shown in FIG. 24, there is a fuselage 101 or the like of an aircraft which is formed as a one piece barrel ((APB). The fuselage 101 includes a skin 102 and a plurality of stringers 103 adhesively attached to the inner surface of the skin 102, and has an opening 104 which becomes a door when the fuselage 101 is assembled as the aircraft and openings 105 which become windows when the fuselage 101 is assembled as the aircraft.
As a technique for manufacturing the above stated structure of the aircraft, there is known a composite barrel section of an aircraft fuselage as disclosed in Patent Literature 1. According to this Patent Literature, the barrel section is defined as “an enclosed shell structure extending 360 degrees about an axis”. To manufacture this barrel section, a mold configured such that a plurality of (e.g., six) tool segments are arranged in a cylindrical shape and supported by using tool fixtures.
Patent Literature 1 discloses as an exemplary manufacturing system of the composite barrel section, a plurality of manufacturing stations are laid out in series and a barrel section tool assembly (hereinafter referred to as a tool assembly) including the mold is introduced into each of the manufacturing stations.
To be specific, firstly, in a stiffener loading station, a plurality of stiffener grooves formed on the respective tool segments are loaded with a plurality of stiffeners, and then the tool segments are loaded into the tool fixtures and supported in a cylindrical shape, thereby forming a single mold (tool assembly in the same Patent Literature). At this time, the tool fixtures are rotatably supported on a tool support structure by means of a plurality of rollers such that the tool fixtures are rotatable along their longitudinal axis.
Then, the mold supported and constructed in the cylindrical shape is transported to a skin laminating station by a tool support structure. Here, the mold is rotated along the longitudinal axis, to laminate fiber tow (bundle of untwisted continuous filaments which is impregnated with thermosetting resin) by a fiber placement machine, thereby forming a laminate (corresponding to skin) on the outer periphery of the mold.
Then, the mold (tool assembly in the same Patent Literature) provided with the laminate is transported to a vacuum station by the tool support structure. Here, a pressure pad is installed on the outer periphery of the laminate, and a vacuum bag is installed on the periphery of the laminate to evacuate the vacuum bag. Then, the mold (tool assembly) attached with the vacuum bag is transported to a curing station by a gantry beam and is treated in an autoclave, to cure the laminate and the stiffener. In this way, the laminate and the stiffener are cured to form a stiffened panel on the outer periphery of the mold.
The mold (tool assembly) provided with the stiffened panel is transported to an inspection station by the gantry beam. The cured laminate (skin) is inspected to check whether or not it has voids or disbonds. Then, the cured laminate (skin) is transported to a trimming station by the gantry beam and subjected to trimming and drilling operations. Then, the tool segments are removed from the stiffened panel and the stiffened panel is returned to the stiffener loading station, and the stiffened panel (tool assembly) from which the tool segments have been removed is transported to a final assembly station by the tool support structure. The stiffened panel is attached with a plurality of frame sections, thereby completing a composite barrel section.
As described above, when the OPB is manufactured, the mandrel of a substantially cylindrical shape is used as the mold. The mandrel is configured in such a manner that a molded product (composite material structure) is molded on the outer peripheral surface thereof to form a hollow space of the OPB which is the molded product using the huge mold. To this end, the mandrel has a structure in which the mandrel is divided into a plurality of segments, for example, six segments, instead of a single huge tubular member. In this structure, the single huge mold need not be used, but the segments may be assembled as necessary. Therefore, this structure is useful in molding of the huge molded product such as the OPB.